Repeater circuit



Jan. 5 1926. 1,568,861 H. A. IML-FEL4 v REPEATER CIRCUIT Filed July'f,1921 2 Sheets-Sheet 1 'H.A. AFFI-:L

, REPEATER GIRQUIT Filed July 2, 1921 zsneets-Sneet 35116710 @Ho/maw# 7M(i i l Patented clan, 5, 1926.

'nutren entre HERMAN a Arran, or encontra, New Yoran, nesrcnoa vronarices: supernatan- AND TELEGBAPH COMPANY, A CGRHATQN Gil .NEW 'YRK--REPEATER CRGUETQ .application filed July m.. Serial. We. emita.

- To all whom z't 'may concern: y

Be it known that I, HERMAN A. Arran, residing at Brooklyn, in 'thecounty tof Kings and -State of New York, have 1nbvented certainImprovements in Repeater Circuits, o which the following is aspeciiication. l

This invention relates to transmission c1rcuits, and more particularlyto transmission 10 circuits of the'generaltype exempliied by two-wayrepeater circuits.

ln repeater circuits of the so-ca-lled 22- type, it has been customaryto differentiate Abetween the sending and receiving channels 16 `bybalancing the channels with respect the line sections,.the well-knovvnhybrid coil and artificial line or network being employed for thispurpose, The problem of balancing a line involves grave oliiiculties, 20however, and frequently the degree of balance is so poor that theamplification must be maintainerl quite low to prevent singing. Inaccordance with the present invention,

it is roposed to etlect two-Way transmission by d ierentiating betweenthe sending and receiving channels on a time basisthat is, byassociating the channels .with the line alternately at a frequency highas compared with the signaling frequency, This results in switching theline at both ends of the repeater at a lrapid 'rate between'the sendingand receiving terminals of the repeater. This will obviously ermit ofoperating the repeater at very higi `gain Without encounteringdiiiculties due to singing, since the problem of repeater singing isvessentially one of discriminating between the oppo# sitely directedchannels. Thisv method of switching may be used either to;supplemeni licthe discrimination clue to balance or may be substituted for thebalancing method.`

An important feature of the present invention resides in the employmentof vacuum tubes for performing the" switching function, the vacuum tubehaving` in this connection the characteristic advantage, as.

compared with mechanical switching means,

of substantial absence of inertiaf thereby permitting of highspeedswitching and absence of contacts troubles. y

More specifically `considered, the invention involves an arrangementvwhereby' the vacuum tube ampliiers in the opposite-ly didem repeaters.

with their attendant rected channels of the 22 repeater circuit arealternately rencleredoperative at a high ref v quency rate by impressingproper operating potentials upon the tubes,

For controlling the amplification of the tubes alternately, the spacecurrents orthe tubes may be supplied from some external" thereiorwbeoperated alternately and not simultaneously.

in important feature of the invention resides in the revision of meanswhereby the" switching e 'the channels oi. repeaters ineluded in tandemin the same circuit may take place simultaneously, or synchronously intime phase with reference to the arrival ofl a given signal impulse atsuccessive tanlt is necessary that.` the switching of all the repeatersin the same circuit take place in such synchronism as otherwise thecircuit might be rendered inoperative clue to one repeater in the1circuit being in nonampliyingconclition upon the arrival of a signalimpulse'passefl by the other repeaters repeating in the same directionwhen in an amplifying condition.

The invention may understood from the following' description,

when reati in connection with the accom-I panying drawing, Figure "i ofwhich illus# trates schematically an arrangement for' controllin Ag thesynchronous switching of a number o repeater sets, and Figs. Zand 3 ofwhich illustrate two forms of repeater sets which may be employed in thecircuit' arrangement of Fig'. l.

Referring to Fi l, L, to. dicate schematicay a number of pairs ofconductors included in the same' cable'or carried along the same poleline or the like.v Each of these pairs of wires may be 'used as aseparate transmission circuit and at suitable po'lnts along the line*each pairs vo' wires, with the exception of the pair L1; may beprovided with repeater sets such asv Re to R5 inclusive, and RJ11 to R5inclusive," etc. 4These repeater sets maybe of the socalled 22type andmay be arranged as pre` viously described so that the amplifiers foramplifying in opposite directions will he operated alternate y. Withoutconsidering L, inclusive in-A -now be more fully Aall of the repeaterstations.

for the moment the means b which this result is accomplished, it willassumed that the amplifiers of each repeater set will be renderedoperative alternately by supplying to the repeater seta high frequencyalternating current, one half-wave of which will cause one amplifier ineach set to be o eratcd and the other half-Wave of which wi 1 cause theother amplifier in the set to be operated. It is essential thattheamplifiers in repeater sets such as R5 and R5 included in the'sameline shall be rendered operative in a given direction in the same timerelation with respect to a voice wave. train successively arriving atthe repeater points. -This involves the provisiono'f some means forsupplying the alternating currents to'repeater sets in the same line 1nsuch phase relation that all the repeaters included in tandem in agivenline, will repeat in the same direction at the -proper time.

In accordance with the present invention. this result is accomplished byutilizing one of the pairs of wires, as, for example. the pair L totransmit alternating current from a given source S over said pair-ofwires to At each repeater station branch circuits through the amplifiersA and A will be provided for supplying the repeater sets. circuits mayinclude phase changers P and P', etc., for regulating the.phase. of thealternating current supplied to the repeater sets. The function of theamplifiers A, A', etc.` is to adjust the amplitude of the cont-rollingcurrents in accordance with the requirements of the repeaters atdiii'erent stations. The branch circuits at the repeater stations willbe providedwith parallel connections leading to each of the repeatersets at a given repeater station. This will permit of one common sourcesupplyingr all of the repeater sets of the system, and it onlynecessitates em loying one'pair of wires out of a large num er of pairsfor transmitting the controlling currents, all of the other pairs beingused'or signaling through repeater sets in the usual manner.

Each of the repeater sets as schematically indicated in Fig. 1 ma be ofthe type illusf trated in Fig. 2 and ig. 3. Referring to Fig. 2, L and Ldesignate transmission line sections which are associated withamplifiers AE and AW through the usual hybrid coil arrangements 10 and10'. Balancing networks o`r artificial lines N and N may be provided asis customary in 22 repeater circuits. The input circuits' 11 and 11 ofthe repeater are connected to the grids 4of vacuum tube` amplifiers AEand AW, respectively, and the output circuits of these amplifiers areassociated through transformers12 and 12 with the outgoing circuits 13and 13 connectedto the midpoints of the hybrid coils. l

The branch T he usual battery or other source of direct current for theplate circuits of the amplitiers AE and AW is omitted in this case, thcspace current being provided by means of t e alternating source S ofFig. 1, leads 14 being associated with the branch circuit including theamplifier and phase changer of Fig. 1. Rectifymg tubes 15 and 15 areprovided for rectifying the alternating currents supplied over the leadsor conductors 14.

AThese rectifiers are ofthe three-element type in which the grid circiit has such a normal potential applied thereto that no space currentflows 1n the plate circuit due to the B battery. When, however, ahalf-wave of the proper potential is applied to the grid,-a

space current is permitted to fiow'in the output circuit of the tube 15or 15 as the case may be, through a resistance 16 or 16. Condensers 17and 17 connect the plates of the rectifying tubes l5 and 15 with theplates of the amplifying tubes AE and AW so that when a pulse-of currentpasses through one ofthe resistanccs 16 or 16', a pulse is induced inthe plate circuitof one of the am, plifiers.

'The operation is as follows: assuming that at a given instant thehalf-'wave of alternating current incoming over the circuit 14 is ofsuch a polarity as to overcome the normal space charge, tending toprevent thc flow of current in the plate circuit of tube 15, it will beapparent vthat a pulse of current will flow from the battery 18 acrossthe filament plate gap of the tube and through the resistance 16. Thealternating half-wave incoming over the circuit 14 is of such a polaritywith respect to the grid of the tube l5 as to increase the space chargein said tube so that no current Hows in the plate circuit thereof. Theimpulse of current flowing in the plate circuit oflthc tube 15 chargesthe condenser 1T so that a potential is applied to the plate circuit ofthe amplifier ANV of such polarity as to cause a pulse of current toflow in the output circuit thereof through the primary winding of thetransformer 12. During the period that th current is flowing through theoutput circuit of the amplifier AW, it is apparent that. the am'-`plifier will be rendered operative "so that speech muy be transmittedfrom the line L t rough the amplifier to the line L.

The amplifier AE isv inoperative at this time as no space current flowsin the output circuit of the tube l5 und hence no potential to drive aspace current through the tube AE is supplied. When the alternating waveof opposite sign is received from the circuit 14, however. the grid ofthe tube 15 has its potential so changed as to 'permit the space currentto flow in said tube, thereby inducing a potential on the plate of theamplifier A E. Accordingly, a space current finiraA through the outputcircuit o the amplifier llO ' trated in Fig. 3, in which case a sourceof'l E'iand voice currents may be transmitted from the' line L to theline L. These oper-l ations: alternate with. each Vsucceeding halt.

Wave of4 alternating current incoming from 'the 'circuit 14 and therepeater set-operates toampli'fy alternately in opposite directions. Ahigh impedance leal; is provided to prevent accumulation of charge oncondensers 17 and 17.

A slightly modified arrangement is illus` space current v18 is includedin the output circuits ci the amplifyingtubes AE and AW and of therectifyingtubes 15 and l5 in series. At a given instant the half-Wave ofalternating-current incoming from the circuit 14 may be of such polarityas to overcome the space charge in tube 15, permitting current to iiowfrom 18'through the plate .circuits of tubes 15 and AW, making thelatter operative as an amplifier. At this in- Stant the voltage appliedfrom circuit 14 to the grid of tube 15 will be of such polarity as tooppose the flow of current in the 4plate circuits of'tubes 15 and AE,and ractically no current will flow, rendering tu e AE inoperative as anamplifier. During the neXt incoming half-Wave of alternating currentfrom 14, conditions will beyrecovered, AE being'operative While AW Willnot function.

-The amplifying tubes, therefore, amplify aland but one is operated at atime.

terna-tel il be obvions that the general prin- It Wi ciple hereindisclosed may be embodied in manyother organizations Widely 'diierentfrom those illustrated, Without departing from the'spirit of theinvention vas defined in the following claims.

What is 'claimed is: In a transmission circuit, a line, a plu,-

rality of 22 repeaters ,arranged'in tandem in lpoint-s.

ytime relation with respect to a voice Wave trainvsuccessively .arrivingat the repeater In a transmission circuit', a transmission line, aplurality of repeaters arranged inV said line invgtuandem, saidrepeaters being separated byline sections of suiiicient length tointroduce a chan e or phase in transmission thereover, an meansoperating said tandem repeaters in the same time relation with respectto a.voi'ce .train successively ar riving at therepeaterpoints to renderthemv alternately operati-ve and inopera'tire"'- for transmission 1n thesaine direction.

' v3. in' a transmission circuit, aline, afplinz rality ot'nne-wayampliers arranged in' said 70' line in tandem, said amplifiers1-beingseparated by -line sections of sucientlen'gth to introduce achange of lphase in tranemission.

i' tliei'eover, and operating means for rendering cach of saidamplifiers alternately op:

'erative and inoperative in the same time relation with respect to avoice Wave succes-r, sively arriving at the amplifier points.

4. in a transmission circuit, a plurality 'of transmission lines,repeaters arranged in 59 tandem in each of said' lines, said repeaters"being separated by line sections of s uicient length to introduce achange of phase in transmission thereover, each repeater includingseparate amplifiers for transmission in opposite directions, alternatingcurrent controlled means for rendering oppositely repeating amplifiersoperative .alternately and in the same time relation with respect to avoice wavetrain successively arriving at the repeater points, and acommon source of alternat'ing current for all of Said repeaters.

5. In a transmission circuit, a plurality of transmission lines,repeaters arranged in tandem in each of said' lines, said repeaters 95being separated by line sections of sufficient length to introduce achange of phase in transmission thereover, each repeater includingseparate ampliiiers for transmission iii Aopposite directions,alternating current 1 controlled means for rendering oppositelyrepeating amplifiers operative alternately, and a common source ofalternating current for operating the controlling means of all therepeaters in the same time relation with respect to a voice wave trainsuccessively arriving at the repeater points.

' 6. -In a transmission circuit, a plurality of transmission lines,repeaters arranged iii tandem in each of said lines, said repeatersbeing separate'dby line sections of sucient length to introduce a changeof phase/in' transmission tliereover, each repeater includ ing separateamplifiers for transmission in opposite directions, alternating `currentcontrolled means for rendering oppositel re-l peating 'amplifiersoperative alternate y, a transmission circuit common to all of saidlines, a source of alternating current for said circuit, connectionsfrom said common cir- 12 cuit to all ofthe tandem repeaters of all of ithe lines, and ineans whereby the controlling means of all of therepeater sets will be operated by the alternating current transmittedover said common circuit in the same time relation with respect to aVoice wave train successively arriving at the repeater points.

7. In a repeater apparatus, line sections over which signaling currentsmay be transmitted, separate amplifiers interconnecting said lines fortransmission in opposite directions, a source of alternating currentindetive.

8. In it repeating system, line sections over which signaling currentsmay be transmitted, seperate vacuum tube am liiers interconnecting seidline sections or repeating in opposite directions, e source ofalternating current independent of said signailingcurrents, Vand meansfor rectifying successive half-waves from said alternating currentsource and for supplying alternate rectified pulses to the outputcircuits of the oppositely repeating am liliers.

In testimony whereo I have signed my neme to this specification this29th dey or" June 1921. 1

HERMAN A'. AFFEL. i

